1. Field of the Invention
This invention relates to a process, apparatus and system for forming a sterile connection (sterile docking) between two tubes.
There are a number of medical and scientific procedures which require the sterile transfer of fluids from one container to another. An example of the need for sterile docking is in continuous ambulatory peritoneal dialysis (CAPD). The CAPD patient has a tube connected to his or her peritoneal cavity via an implanted catheter. A tube from a bag of fresh dialysis solution is connected to the patient's tube. The fresh dialysis solution is drained from the bag into the patient's peritoneal cavity where it remains for about 3 to 4 hours. After this treatment period, the spent dialysate is drained back into the empty bag which is then disconnected from the patient's tube. A bag of fresh dialysis solution is then connected to the patient's tube and the procedure is repeated.
Sterile connections during CAPD procedures would minimize the occurrence of peritonitis. The process, apparatus and system of this invention can be employed with various medical devices including catheters, urinary drainage bags, treatment bags such as those used in IV therapies for administering antibiotic, bacteriostat, or other medication, as well as for sterile connections involving blood bags. At present, blood from a donor is drawn into a primary bag which can be joined to one or two satellite bags, all connected and sterilized before use. These satellite bags can be used for holding blood separated components, such as plasma or platelets; treating agents, such as bases, buffers, stabilizers for cell metabolism, other preservatives, or rejuvenants; or washes to remove a treating agent or other contaminant. The process, apparatus and system of this invention permits blood processing without compromising sterility, limiting storage life, or requiring the preconnection of a multitude of bags, all wet-sterilizable, without knowing which, if any, will be used.
2. State of the Art
U.S. Pat. No. 4,369,799 (Spencer) discloses a process, apparatus and system for sterilely connecting two sterile, closed end tubes. The process comprises urging a hot cutting means through each tube and simultaneously forming a continuous molten seal between a heated cutting surface and a transverse section of each said tube thereby maintaining a seal between the interior and exterior of the tubes, aligning the tubes with each other and joining the respective molten ends of the tubes together to form a joint between the tubes, both while maintaining said seal. The apparatus comprises a cutting means, means adapted to heat said cutting means, a pair of mounting blocks adapted to receive and hold two tubes to be joined, means to provide movement between said blocks and said cutting means to a position such that the cutting means is between said blocks and traversing where the blocks are adapted to receive tubes, means adapted to realign said blocks to a position where two different tube ends are aligned with and facing each other, and means to separate said blocks and the cutting means while urging the blocks together. The patent teaches that during the connection operation there should be no significant visible deformation of the tubes and that, in order to obtain a secure dock, the tubes to be joined must not contain more liquid than a thin film on the walls at or near the locations where they are to be cut and joined.
U.S. application Ser. No. 599,324, filed on Apr. 12, 1984, discloses a process, apparatus, and system for the sterile connection of closed end tubes (flat tube welding). The process comprises flattening a section of each tube to urge inside walls of each tube into contact, urging a hot cutting means through the flattened section of each tube thereby temporarily sealing together the inside walls of each tube and providing molten tube ends, aligning the tubes to be connected with each other, joining the desired molten ends of said tubes together to form a joint between said tubes, and cooling said joint and then subjecting it to stress to open the temporary seal in each tube, thereby providing fluid communication between the joined tubes.